Many industrial, commercial, and household applications require the breaking up of relatively large objects into smaller pieces. The reduction process is variously referred to as cutting, chipping, shredding, mulching or grinding, depending in part on the size of the end product. Cutting and chipping is historically accomplished by chippers using relatively few chipper knives mounted directly onto a rotating disc and a bed knife, and produces pieces ranging up to about 3/4 to 11/2 inches in size.
One of the major issues with respect to the design of such devices is maintenance. Maintenance and adjustment of chipper and bed knives can be extremely cumbersome. In many chippers, a team of two men is required to change the chipper knives, by working through holes in the side of the chipper body. Long feeler gages must be used to adjust the gap between the knife and bed knife.
Another issue is the design and maintenance of the feed rollers. Traditionally, dirt and trash is carried into the chipper with the in-feeding of the brush and wood. This dirt always falls into the lower feed roller. If not cleaned out, it will lock up the feed roller such that it cannot rotate.
To access these various components and areas, some manufacturers of the disk-style machines often hinge the upper half or quarter of the chipper body for the servicing of knives. Such machines include the Model 1230 Chipper manufactured by Vermeer and the Model 90 Brush Bandit manufactured by Bandit. However, the bed knife remains difficult to adjust. Some other manufacturers such as Carlenburg for Mittsonmurrel Drum Machines and Gravely Disk Chippers enable the servicing of knives by hinging the feed hopper or sliding the upper feed roller vertically in a slide with weights or spring down pressure. In many of these systems, replacement of the feed rollers requires one to crawl inside the machine and awkwardly perform the replacement. Morey, U.S Pat. No. 5,005,620 discloses an upper feed roller pivoted from the chipper drum center-line (called the pivoted down stream). Houston, U.S. Pat. No. 4,390,132 discloses a trailing arm that is pivoted from a point above the feed path. A hydraulic cylinder and compression spring force engagement with the tree (feed stock). To reduce the frequency of required access, most manufacturers of chippers with lower feed rollers simply place an auxiliary frame or compartment that traps the dirt and debris.